SPHEROIDAL VIBRATIONS OF AR-CLUSTER ISOMERS ANALYZED BY MOLECULAR-DYNAMICS CALCULATION

The vibrational motion of Ar clusters (Ar-n, n = 20, 23, 25, 27, and 3 0) having isomers in a variety of shapes was simulated by the molecula r dynamics method. The intensities of the breathing and quadruple sphe roidal vibrations following the breathing-mode excitation of the isome rs were calculated. It was found that only the breathing vibration was excited in nearly spherical isomers, while significant excitation of the quadruple spheroidal vibration as well as the breathing vibration was observed in nonspherical isomers. The degrees of sphericality of t he isomers were assessed by use of their principal moments of inertia. The excitation of the quadruple spheroidal vibration was found to be closely related to the degrees of sphericality of the isomers.